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Military Orions (nuclear pulse propulsion)

agricola64

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RP1 said:
we can substitute the nuclear bombs previously used for the atmospheric stage of the flight for thermobaric bombs (FAB) like the Russian Father Of All Bombs (FOAB) since these have the same power as a small nuclear bomb but with no fallout
It's not raw power that matters, it's power per unit weight. FOAB has a mass of several tonnes - assuming Wikipedia is correct (the numbers seem to be referenced), 7 tons for 44 tons yield. Offhand, a multi-kiloton nuclear device will have a mass of a couple of hundred kilograms.

RP1
the only point where i could see chemical propellant used in an orion flight system would be if you insist on take off from ground without using chemical rockets for intal lofting ..

place the orion over a deep pit, fill it half with a few thousand tons of AMFO, ignite .. this might reduce fall out since the next pulse (the first nuclea pulse) would be already a little away from ground ..

but it is a silly application .. putting a few SRB boosters underneath would do the same thing at better performance
 

Orionblamblam

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amsci99 said:
In practice, would the 2nd stage shock absorbers be enclosed in a shroud to protect them from space debris?
There would be individual meteoroid shields. That's why the upper portions of the tubes are so much larger in diameter than the pistons... they housed telescoping shields. Once the propulsion system was shut down, the shields would extend from the upper tubes to enclose te pistons. The first stage shock absorber "airbags" would be depressurized, and the plate pulled in tight against the intermediate platform to "hide" the airbags.
 

Orionblamblam

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agricola64 said:
one thing i did not understand about the battleship orion reconstruction was the complex launcher system for the Casaba Howitzer with aimed launch tubes
What I tried to do was rationalize the design as described. Sadly, the description of the CH's was exceptionally vague, but both written and verbal descriptions of the CH's mention some sort of noticable "emplacements." Were they simple VLS-like launch ports.... as I did with the Minuteman warheads - then they would not really stand out.

Secondly, the presumption is that the safest place to be around a detonating CH would be directly behind it, as opposed to off to the side. This may, of course, not be accurate... for all I know there were weird "lobes" in the blast. If you fired straight out of a fixed tube and then oriented, the bomb would present some side aspect to the Orion. But if you directed the CH away from the ship with an aimable launcher, the chances are greater that the bomb will have to change its attitude much less prior to detonation, keeping the Orion more directly behind it.

Thirdly, with an aimable launcher, most of the important attitude control will be done by the launcher itself. The onboard ACS will be needed for fine control. But if launched from a fixed tube, the onboard ACS will have to do both coarse and fine attitude control. This will be both heavier and less reliable. An aimable "bazooka" should be pretty reliable.

Until more info on CH comes out (any decade now, I'm sure), this is all specualtion
 

sferrin

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Something else to keep in mind is the timeframe the thing was conceived. Back in those days the only thing they used a VLS for was SLBMs. Everything else used trainable launchers (except for a few Russian launchers on the Kara and Krest II classes) so it would stand to reason they'd be in that mindset. Besides, you also have to remember that in space there's no atmosphere for wings to work with so any change in direction would have to come from onboard fuel which would increase the weight. Much simpler to train it in the direction of the target and fire so any course corrections are kept to a minimum.
 

agricola64

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Orionblamblam said:
Secondly, the presumption is that the safest place to be around a detonating CH would be directly behind it, as opposed to off to the side. This may, of course, not be accurate... for all I know there were weird "lobes" in the blast. If you fired straight out of a fixed tube and then oriented, the bomb would present some side aspect to the Orion. But if you directed the CH away from the ship with an aimable launcher, the chances are greater that the bomb will have to change its attitude much less prior to detonation, keeping the Orion more directly behind it.

Thirdly, with an aimable launcher, most of the important attitude control will be done by the launcher itself. The onboard ACS will be needed for fine control. But if launched from a fixed tube, the onboard ACS will have to do both coarse and fine attitude control. This will be both heavier and less reliable. An aimable "bazooka" should be pretty reliable.

Until more info on CH comes out (any decade now, I'm sure), this is all specualtion
not necessarily ..

the idea is a little hard to explain without being able to draw on a sheet of paper, but consider this

the CH us ejected and reorients itself towards the target, then inites its engine for separation (this implies that the target is in the hemisphere visible from the VLS location on the orion)

now draw a line from the orion to the target - the threat axis .. after reorientation and igniting the CH will follow a course that is parallel to the thrweat axis, offset by the ragius (and a little something) of the orion

if the detonation safety distance is large enoug (lets say at least 100 times the radius of the orion) the gemetry beomes a very narrow trinagle with almost no difference between the threat axis and the line of view from orion to the CH .. the orion basicaly IS seeing the back end of the CH exclusively ..

i hope the explanation is clear ..

i do understand the idea of minimising the ACS role - it will use less fuel .. otoh it is there already and making the tank a little larger will very likely still be lighter then the mechanics of the launcher
 

Orionblamblam

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agricola64 said:
the CH us ejected and reorients itself towards the target, then inites its engine for separation
This would require two separate propulsion systems... an ejector (likely either a cold or hot gas "gun" on the ship) and a warhead-based system. What I assumed in mine was a fast-acting hot gas thruster that operates entirely within the confines of the launch tube. In that case, any thrust misalignments or CG issues become moot, as those side forces are taken up by the launch tube... not expended in throwing the warhead off course.


i do understand the idea of minimising the ACS role - it will use less fuel .. otoh it is there already and making the tank a little larger will very likely still be lighter then the mechanics of the launcher
Maybe, maybe not. Without going through the whole design and optimization process, and numbers woudl be the purest unwarranted speculation. But if you have six CH launchers and, say, a hundred CH warheads on board, that's about seventeen warheads per launcher. So if the additional complexity of an aimable launcher is, say, 500 pounds, then to match the same total weight the additional weight for the more-capable-ACS warheads would be 29 pounds. Given that the CH warheads are almsot certainly very dense little nuggets weighing on the order of 500 pounds, in order to provide the sort of attitude control required might easiy add another 30 pounds. Remember, it's not just slightly larger fuel tanks, it's also substantially higher thrust (thus larger & heavier) thrusters, plumbing and power systems (and very likely larger nitrogen pressurization systems).


In general terms, if you have a large, fixed emplacement (such as a battleship), what you'd generally prefer if to have a weapons system that keeps the expensive and complex stuff on the ship, and chucks simple&stupid at the enemy. That's what you have with a gun... a complex, heavy item that stays behind. Even with missile systems, you generally try to leave as much of the complexity on the ship as possible... the most complex weapons, such as the Standard missile that was recently used to take out a satellite, leaves most fo the tracking functions to the ship, and only carries what it absolutely *needs.*

But... who knows. Hopefully someday we'll know for sure. Very likely if i ever do see photos of the Orion battleship model and/or diagrams of the complete CH weapons system, my reaction will be one of "Huh."
 

Orionblamblam

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sferrin said:
Something else to keep in mind is the timeframe the thing was conceived. Back in those days the only thing they used a VLS for was SLBMs. Everything else used trainable launchers (except for a few Russian launchers on the Kara and Krest II classes) so it would stand to reason they'd be in that mindset.
Back In The Day:


The missiles were stored vertically and rose up from below the launchers... you can see the doors to either side of the pedestal.

Today:


The missiles are launched straight out of the tubes.

My bet is that in 1960, the Orion was designed with 1960-era practices. Were the design done today, or the Orion battleships refitted today, they'd use more modern design practices.
 

sferrin

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Yep. Well aware of how they use to do it and how they do it today. ;)
 

chimeric oncogene

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Would a similar gas launch system been used to toss out the warhead RVs?

If the Orion was used as a gargantuan MIRV bus (instead of carrying smaller MIRV buses, which might also work but would cost more), one would imagine that it would need a helluva precise altitude control system and RV launcher (can you make a gas gun with low acceleration and very precise adjustable muzzle velocity?) to put warheads on target with reasonable accuracy (100-300m CEP?). Would unguided rockets work equally well (methinks not, but I know but little)? Or would Orion just stick a warhead out on an arm, let go, and maneuver?

The same question could be asked of the DynaSoar bomber, or the AXE Pershing II hypersonic glide vehicle airfield attack weapon.

How were the nuclear RVs proposed to be ejected from the Orion battleship?
 
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